Document FR 2 575 708 describes an example of such a seat. The seat sliding along the runner makes it possible to define a normal in-use position, in which an occupant can sit in the seat, and a loading position, in which the seat is moved forwards and tilted, e.g. for loading objects behind the seat. In that position, the seat nevertheless still takes up a large amount of space, which prevents easy access to the space situated behind the seat, and prevents bulky objects from being stowed.